Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
Day 1 Wind Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
30 %
11,451
5,923,875
Detroit, MI...Toledo, OH...Warren, MI...Sterling Heights, MI...Ann Arbor, MI...
SPC AC 201255
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0755 AM CDT Thu Apr 20 2017
Valid 201300Z - 211200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS
SOUTHEAST LOWER MI AND FAR NORTHEAST IN/NORTHWEST OH...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
SOUTHERN GREAT LAKES AND OHIO VALLEY...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
SOUTHERN PLAINS...
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE
SOUTHERN HIGH PLAINS TO THE NORTHEAST STATES...
...SUMMARY...
Severe storms capable of producing damaging winds, hail, and perhaps
a tornado or two will be possible across parts of the southern Great
Lakes region and Ohio Valley this afternoon and early evening.
Isolated severe storms capable of producing large hail are also
possible across parts of the southern Plains tonight.
...Great Lakes and Ohio Valley...
The remnants of an MCS continue to move eastward across lower MI and
far northern OH early this morning, with the somewhat stronger and
more sustained convection occurring near a west/east-oriented warm
front that parallels the IN/MI/OH border vicinity. An upstream upper
trough over the Upper Midwest will continue eastward toward the
Upper Great Lakes by this evening. A surface low over eastern IA
early this morning may modestly deepen as the warm front spreads
slowly northward across southern Lower MI and the Lake Erie
vicinity.
Some concerns exist regarding the degree of destabilization later
today ahead of the approaching cold front, particularly given
observed mid/high-level cloud cover upstream, which is largely
related to a weak eastward-moving impulse and convection over MO.
Furthermore, near-frontal convergence should remain modest given the
aforementioned impulse and tendency for a pre-cold-frontal veering
of low-level winds.
Regardless, modest destabilization should occur this afternoon just
ahead of the front with as much as 800-1200 J/kg MLCAPE expected
around peak heating from IN into southeast lower MI and northwest
OH. Strengthening west-southwesterly winds through a deep layer,
with effective shear magnitudes reaching 35-40 kt late in the
afternoon, could support both weak/short-duration supercells and
eastward-moving clusters capable of damaging winds and some hail
this afternoon and early evening. A tornado risk may exist as well,
particularly across southeast lower MI and far northeast IN/far
northwest OH in closer proximity to the surface low and warm front
where low-level SRH will be maximized.
...OK and northeast NM/TX panhandle...
A southeastward-moving front is expected to decelerate and stall
across OK and western north TX by this evening. Aided by nocturnally
increasing isentropic ascent, storms should increase and intensify
in a WSW/ENE-oriented corridor across OK this evening just north of
the surface front. Ample shear through the cloud-bearing layer,
along with relatively steep mid-level lapse rates and as much as
1500-2000 J/kg of MUCAPE, will support elevated supercells capable
of large hail.
Farther west, while some spatial uncertainty exists regarding the
stronger convection late tonight (especially given the highly
elevated nature of the storms), various convection-allowing models
support the development of potentially severe convection as far west
as northeast NM late this evening and overnight. This would be
supported by the gradual amplification of an upstream Rockies
trough, with steepening mid-level lapse rates supported by a pocket
of cooling mid-level temperatures. Severe hail appears possible late
this evening and especially overnight across parts of northeast NM
into the TX panhandle.
..Guyer/Jewell.. 04/20/2017
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